Class: PgPipeline::Runtime::Semaphore

Inherits:
Object
  • Object
show all
Defined in:
lib/pg_pipeline/runtime/semaphore.rb

Instance Method Summary collapse

Constructor Details

#initialize(limit) ⇒ Semaphore

Returns a new instance of Semaphore.

Raises:

  • (ArgumentError) 


6
7
8
9
10
11
12
 
# File 'lib/pg_pipeline/runtime/semaphore.rb', line 6

def initialize(limit)
  @limit = Integer(limit)
  raise ArgumentError, "limit must be >= 0" if @limit.negative?

  @available = @limit
  @waiting = WaitList.new
end

Instance Method Details

#acquire ⇒ Object 



14
15
16
17
18
19
20
21
22
23
 
# File 'lib/pg_pipeline/runtime/semaphore.rb', line 14

def acquire
  wait
  return @available unless block_given?

  begin
    yield
  ensure
    release
  end
end

#release ⇒ Object 



25
26
27
28
29
30
31
32
33
 
# File 'lib/pg_pipeline/runtime/semaphore.rb', line 25

def release
  if (node = @waiting.shift)
    node.grant!
    node.resume
  else
    @available += 1
  end
  @available
end